JPS60159669A - Radar responder - Google Patents

Abstract

PURPOSE:To detect a respond from a responder and to identify it individually by generating two kinds of signals for sweeping at a constant fixed period responding to a radio wave from a search radar and at a period matching with a specific identification code signal. CONSTITUTION:A gate signal generating circuit 4 sends a gate signal to a gate circuit 7 in response to a detection signal, and electric power is supplied to a transmission part 7. At the same time, a start signal is supplied to an FM modulator 6, which generates a saw-tooth wave modulation signal to supply the transmission part 5, thus generating a radio signal for responding which makes a sweep at frequencies f1-f2. The identification signal is added to the radio wave from the radar responder and a radar response signal, and a number code signal for individual identification is arrayed successively to the radar response signal and sent out as a sweep signal similar to the radar response signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention provides a radar response device that is effective for indicating the position of a pulse modulation search radar used in search operations for maritime rescue from the side of a victim. It is related to.

(Prior art) This type of device was previously disclosed in Japanese Patent Publication No. 55-81480 (
There was something shown on the radar marking device).

In this device, when it is irradiated with radar pulse radio waves from the search radar, the radar response device carried by the victim is activated and the radar response repeatedly sweeps the frequency range of the search radar at a fixed period. Send a signal. When the search radar receives this radar response signal, it draws so-called continuous bright spot signals lined up at regular intervals on the radar scope, making it possible to distinguish them from other radar reflectors and determine the whereabouts of the victim.

Since the radio wave intensity of the radar response signal is very weak, this device can be packaged in a small size as a whole and can be supplied at low cost, so it can be used in a wide range of applications such as lifeboats on large ships, small ships, leisure ports, etc. It is seen as. The problem when a large number of such systems are used over a very wide range is how to suppress unnecessary and unauthorized calls and ensure appropriate operation.

(Summary of the invention) This invention was made in view of the above problems,
Each radar response device is configured to emit an identification signal along with a radar response signal, so that the usage status of the radar response device can be monitored as necessary.

The radar response device according to the present invention: ■In order to avoid complication of the device, it is preferable that the individual identification signal be in the same signal format as a normal radar response signal. A preferred method is to transmit a continuous bright spot signal and modulate the signal with a number code.

(2) However, assuming a scale of, for example, one million subscribers, there is a problem in that the length of the number code will be close to 60 bits. In other words, the radar response device transmits a radio wave signal consisting of a continuous bright spot signal, which is a radar response signal, followed by a nearly 60-bit identification signal, for every radar pulse hit, so there is no mischief on the radar scope. Not only are long continuous bright spot signals lined up, but the number of radar pulse hits of the search radar is limited due to the need to have a long identification signal, and the number of repeated receptions on the search radar side is reduced, so it is received isometrically. It causes a decrease in sensitivity.

■Therefore, when the distance between the search vessel and the radar transponder is far, the identification signal may be omitted from the radar transponder, or a portion of the number code signal that can be easily distinguished may be transmitted from the radar transponder. Only this signal is transmitted as an identification signal. When a search boat approaches a radar response device, all elements of the number code are automatically switched and transmitted as identification signals.

Based on this idea, we are trying to solve the above problems.

(Embodiment of the Invention) FIG. 1 is a block diagram of an embodiment of a radar response device according to the present invention. In the figure, (lb) is a receiving antenna, (2) is a receiving unit that receives and detects radar signals from the search radar and sends out a video signal related to the radar signal, and (3) is a video amplifier that The signal amplifying circuit (4) is a gate signal generation circuit, which is controlled by the output signal of the video amplifier (3) and supplies gate signals to each section in response to the received radar signal.

In addition, (1a) is a transmitting antenna, and (5) is a transmitting unit for FM
In response to the sawtooth modulated signal from the modulator (6), the transmitter (
5) The oscillator contained in the oscillator is subjected to FM modulation. (7) is a gate circuit, which is a gate signal generation circuit (
The transmission is controlled by controlling the power supply from the heart source (9) to the transmitting section under the control of the gate signal from the transmitter.

Next, the operation will be explained.

Radar pulse radio waves from the search radar are sent to the receiving antenna (1
b) and is guided to the receiving section (2) and detected.

The situation of this detection pulse is shown in FIG. In the figure, τ.

is the time required for the rotating search radar antenna to make one revolution, and g is the repetition period of radar pulse radio wave emission. Since the beam width of the search radar antenna is usually around ±10, it will continue to receive radio waves during the time TR corresponding to ±10 when the search radar is facing the radar response device, resulting in a detection output of PH+P2. ' Pnr (
(hereinafter referred to as (P;)) is obtained. In this case, r is 'Tjj5''180.

When the search radar approaches the radar transponder, the detection output (Pi) is obtained as the output of the receiver (2) even if the search radar antenna points to the side due to the influence of the side rods of the search radar antenna. The time TJI during which the detection output is obtained gradually becomes larger and becomes τ. It will move closer to .

Based on this detection output, a gate signal generating circuit (4) generates gate signals necessary for each section. Regarding this, it is necessary to first explain the relationship between the received signal and the transmitted signal based on FIG. 8. In the figure, the same reference numerals as in FIG. 2 indicate the same or equivalent parts. (a) shows the radar pulse radio wave emitted from the search radar at time τ, and (a) shows the radio wave detected by the radio wave response device. The distance @L from the search radar to the radar transponder is CTc (C: speed of light). However, for convenience of explanation, the delay time within the radar response device will be ignored here.

In response to the detection signal, a gate signal is sent from the gate signal generation circuit (4) to the gate circuit (7), power is supplied to the transmitter (7), and a start signal is also applied to the FM modulator (6). As shown in b), a sawtooth modulated signal with a similar waveform is created and applied to the transmitter (6), resulting in a soft)
A response radio signal is created that sweeps from frequency f to f as shown in FIG. Note that fl and f are set sufficiently wide to sufficiently cover the reception frequencies of various types of search radar receivers.

This radio signal reaches the search radar via the transmitting antenna, but the reception frequency of the search radar is fs between fU and f2.
Therefore, on the search radar side, the sweep frequency of the radio wave signal is detected every time it passes f8, and the video signal as shown in (2) (in the figure, Q1) is detected.

Qs-Qs, denoted by Q4) is detected and drawn as a continuous bright spot on the radar scope. Td is the time from the rise of the sweep until the sweep frequency reaches fs.

This binding from f to f is repeated a predetermined period and number of times each time the radar response device receives a radar pulse signal from the search radar. In the example shown in Figure 1, the sweep period is τ and the number of repetitions is 4, so four consecutive bright spots are usually seen on the radar scope of the cutting vessel.

The gate signal to the receiving section (2) is to prevent the received signal from entering the receiving section again and falling into a state like self-sustaining oscillation when the received signal is detected and transmitted. received before transmission begins.

A gate signal is supplied to the receiving section (2) to put the section (2) in a non-operating state and return the receiving section (2) to an operating state once the transmission is completed.

Now, in the present invention, an identification signal is added to the radio wave signal from the radar response device in addition to the radar response signal in the device that performs the above basic operation, and a number code for individual identification is added to the radio wave signal from the radar response device. The signals are combined with the radar response signal, arranged, and sent out as a sweep signal similar to the radar response signal.

FIG. 4 shows an example of the relationship between each signal.

In FIG. 4), the conventional radar response signal is displayed as signal A, and the identification signal is displayed as signal B. In order to distinguish between signal A and signal B, a time interval of two sweep times is provided. In this example, the number code of the identification signal indicates (1, 1, 0, 1). In addition, T in Figure 4 (b)
pl is the duration of signal A, Tp2 is the duration of signal B,
Tpo is the space time between signal A and signal B.

FIG. 5 shows the configuration of an FM modulator that generates the signals A and B. @υ is the input terminal of the FM modulator that receives the activation signal from the gate signal generation circuit (4), - is the code generation circuit that generates a code signal that is a combination of signals A and B, and is connected to the continuous control circuit ( Read only memory (622) (hereinafter ROM
A predetermined one of the code signals stored in the computer is designated and read out.

In the example shown in Figure 4, signal A is (1, 1, 1, 1) and signal B is (1, 1, 0, 1), so including the space between signal A and signal B, (1, 1 ,1,1,0,0,1,1,
01) is stored in the ROM (622) and read out under the control of the successive output control circuit (621) when necessary conditions are met.

- is a trigger generation circuit, and - is a sawtooth wave generator, which receives the code signal and generates a sawtooth wave signal that changes as shown in FIG. 4(b).

Next, the overall operation will be explained. - The transmitter 15) transmits f according to the waveform from the FM modulator (6).
Since the frequency sweep is performed from l to f2, the ROM (
622) is detected by the search radar and drawn on the radar scope. by this,
Similar to the conventional system, the continuous bright spot signal by signal A allows the radar response signal from the radar response device carried by the victim to be received separately from the reflected waves from other reflectors, and the radar response signal by signal B can be received by the radar scope. The content of the bright spots above allows for relatively simple identification, for example, the identification of a ship in distress up to its seed spot.

The contents of the code signal can be selected and changed arbitrarily by setting the code to be stored in the ROM (622) and specifying its read address, but if you try to perform individual identification directly as mentioned above, the length of the code signal This results in the problem that the distance becomes very long, making direct observation on a radar scope difficult, and that the number of hits is limited, resulting in a reduction in isometric reception sensitivity.

We will solve this problem as follows.

The first method is to send an identification signal indicating only the type of ship in distress as signal B when the radar transponder is far from the search radar, and when it approaches and T++ becomes large and τ0, the readout control circuit (621) Approximately 50 ROMs (622) are switched by the control for individual identification.
This is a method in which the identification signal consisting of bits is fully transmitted as signal B.

Since radio waves from the radar transponder can be stably received when approaching the victim, the search vessel can confirm the content of the individual identification code signal by photographing the bright spot signal on the radar scope.

It should be noted that confirmation of the individual identification code signal is not necessary during the search for the victim, but only needs to be done after the position of the victim has been confirmed. It's very unnecessary. What is needed are search vessels such as patrol vessels from enforcement agencies, so if only these vessels are equipped with a device that extracts the video signal of the search radar device, processes it, and deciphers the code signal, the above will be achieved. There is no need to use the primitive method of confirmation by taking photographs.

The second method is to cyclically and sequentially switch the contents of the code signal of signal B while continuously receiving radar pulse radio waves from the search radar, so that each cycle represents a code signal for individual identification. Good too. For example, in the case of switching that takes one cycle in 1o steps, the signal B is made up of 5 bits, and one step is advanced every approximately 100 hits of the detection signal of the radar pulse radio wave, so that one code signal for individual identification is made up in 1o steps. . Then, from the search ship, 1
When receiving radar pulse radio waves of 000 hits (=100 hits x 10), the radar transponder can complete sending out the code signal. In this case, the time required for the search boat to confirm the code signal of the victim's radar response device is usually determined by the repetition frequency of the radar device being 1
Since it is about 000 pps, it takes about 1 second.

The first method and the second method described above are based on the switching of RORl (622) by the code generation circuit @(621) in accordance with the detection status of the detection signal @(PH). control.

FIG. 6 is a configuration example for explaining such control. In the figure, the same reference numerals as in FIG. 6 indicate the same or corresponding parts. (6211) is the first timer and the detection signal (Pi
If the detection signal is input continuously for a predetermined number of times or more, an ON signal is output to the output, and if the detection signal does not continue for a predetermined number of times or the input of the detection signal stops, a (JFF signal is output) to the output. (62
12) is a second timer that cooperates with the AND circuit (6210) to output an ON signal to the output if the detection signal (Pl) continues for a predetermined number of times or more after the output of the first tie v (6211) is turned ON. In other cases, the output is controlled to be the same as the OFF signal. When the second timer (6212) issues an ON signal, the first timer (6212)
11) is reset and returns to the starting state. (6218
) is the first logic circuit, and the first timer (6211) is O
How the FF outputs, the detection output supplied to the input terminal (Pi
) to the input terminal (6221) of the ROM (622), and the code signal stored corresponding to the input terminal (6221) to the output terminal (6224). (6214) is a second logic circuit, and when the first timer (6211) is ON output, the detection output (Pi is ROM) is supplied to the input terminal.
(622) is led to the input terminal (6222), and the code signal stored corresponding to the input terminal (6222) is led to the output terminal (6224).

Next, the operation will be explained. Figure 7 (4) is the detection output (pi)
When the number of continuations of is small, Fig. 7(B) shows the detection output (Pi
) is an explanatory diagram when the number of continuations is large.

When the number of continuous detection outputs (Pi) is small, both the first timer (6211) and the second timer (6222) remain in the OFF output as shown in FIG.
The first input terminal (6221) of M (622) is driven, and the first code signal (for example, a simple ship type code signal) is sent out as the signal B.

Therefore, the radar response signal is the radar response signal (No. 4R A).
and a first code signal] (signal B)
is sent.

When the number of continuations of the detection output (PI) increases, the first timer (6211) goes from the OFF state to the ON state as shown in FIG. There is an input, and then the input terminal (6222) moves to the input terminal (6222), so the input terminal (6222) changes to the input terminal (6222).
The system of the first method can be configured by setting the signal B corresponding to the input terminal (621) to a simple configuration and setting the signal B corresponding to the input terminal (6222) to an individual identification code signal.

If the number of continuations of detection output (Pi) is very large, the second timer (6212) outputs the first timer (6211).
By resetting and returning to the original state, the signal B can be repeatedly switched between a simple code signal and an individual identification code signal.

In the system of method @2, by providing the required number of successive control terminals at the input terminal of the ROM (<622) and storing the corresponding code signals, the method according to the first method is applied according to the number of consecutive detection signals. Make sure to switch accordingly.

As described above, when the radar response device according to the present invention receives a radar pulse signal from a search radar, it responds by controlling an oscillator that generates a signal that repeatedly sweeps so as to cover the receiving frequency of the search radar. Since this repeated sweep is controlled by the radar response signal and the identification signal, the response from the radar response device can be detected while distinguishing it from other radar reflected waves.
Radar transponder identification can be performed. In addition, the content of the identification signal included in the repeated sweep signal is switched depending on how the detection signal from the search radar continues, making it possible to transmit multiple types of code signals. In addition to detection, it is possible to maintain reception sensitivity and perform complex individual identification.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the radar response device according to the present invention, FIG. 2 is a diagram illustrating the state of detected pulses when receiving an order for radar pulse radio waves in the radar response device, and FIG. , a diagram illustrating the relationship between the received signal and the transmitted signal in the radar response device, FIG. 4 is a diagram illustrating the relationship between an example of each signal in the radar response signal, and FIG.
FIG. 6 shows an example of the configuration of an FM modulator, FIG. 6 shows an example of the configuration of a code generation circuit, and FIG. 7 is a diagram explaining the operation of the code generation circuit of FIG. (lb)...Receiving antenna, (2)...Receiving section,
(3)...Video amplifier, (4)...Gate signal generation circuit, (la)...Transmission antenna, (5)...
Transmitter, (6)...FM modulator, (7)...gate circuit, (8)...power supply, bag...code signal generation circuit, (621)...sequential control circuit, ( 622)... Read-only memory, -... Trigger generation circuit, -...
・Sawtooth wave generation circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 L-----------1--J Figure 6 Figure 7 Timer 2-11□---- −−−−−□−−−□−+2□
Mr. Commissioner of the Patent Office 1. Display of incident Patent application No. 59-1 (i2ti2 No. 2
, Title of the invention Radar response device 3, Person making the amendment 11) Light+i-1 Features F' of 4 Claims, U, Detailed description of the light, and n of the drawings, °1 Simple description li ,
'J 7. List of attached documents (1) One or more documents indicating the scope of patent claims after correction Claims 11) Radio waves that sweep a predetermined frequency range multiple times in response to radar pulse radio waves from a search radar In the device that generates the signal, the radio signal is characterized by being composed of a first signal that repeatedly sweeps at a fixed constant cycle, and a second signal that sweeps at a cycle that matches a predetermined identification code signal. radar transponder. (2) In a device that responds to radar pulse radio waves from a search radar and generates a radio signal that sweeps a predetermined frequency range multiple times, the radio signal includes a first signal that repeats the sweep at a fixed constant cycle and an identification code signal. A radar response device characterized in that the second signal sweeps at a period matching the element code signal constituting a part of the radar response device. (3) The second signal in one radio wave signal generation is composed of one element code signal obtained by dividing the identification code signal, and the elements are sequentially switched in response to multiple radio signal generation. A patented radar response device characterized by: (4) A patent characterized in that each element code signal of the identification code signal in the generation of a radio wave signal is switched only when the duration of reception of radar pulse radio waves from a search radar continues for a predetermined period of time. A radar response device according to claim 2 or 8.

Claims (3)

[Claims] (1) In a device that responds to radar pulse radio waves from a search radar and generates a radio signal that sweeps a predetermined frequency range multiple times, the radio signal consists of a first signal that repeats the sweep at a fixed fixed period, and a predetermined frequency range. A radar response device comprising: a first signal that repeatedly sweeps at a period matching a predetermined identification code signal; and a second signal that sweeps at a period matching a predetermined identification code signal. (2) In a device that responds to radar pulse radio waves from a cutting radar and generates a radio signal that sweeps a predetermined frequency range multiple times, the radio signal includes a first signal that repeats the sweep at a fixed constant cycle and an identification code 4d. The second sweep is performed at a period matching the element code signal that constitutes a part of the signal.
A radar response device characterized by comprising a signal. (3) The second signal in one single wave signal generation is composed of one element code signal obtained by dividing the identification code signal, and the elements are sequentially switched in response to multiple radio signal generation. A radar response device according to a patent characterized in that it performs the following. (4) A patent characterized in that the switching of each element code signal of the identification code signal in the generation of a radio wave signal is performed only when the duration of reception of radar pulse radio waves from a search radar continues for a predetermined period of time. A radar response device according to claim 2 or 8.